Polyimide resins for high temperature wear applications

Abstract

Polyimide resin compositions that contain an end-capped rigid aromatic polyimide, graphite and, optionally, a filler selected from sepiolite, attapulgite, kaolinite, or a mixture thereof, are found to exhibit low wear at high temperatures. Such compositions are especially useful in molded articles that are exposed to wear conditions at high temperatures such as aircraft engine parts.

What is claimed is: 
     
       1. A method of preparing a wear resistant polyimide, comprising
 (a) end-capping, with phthalic anhydride, or a derivative of phthalic anhydride, as represented by the structure of the following Formula (IV) 
 
       
         
           
           
               
               
           
         
       
       wherein R 4 , R 5 , R 6 , and R 7  are each independently H, Br, Cl, F, alkyl, alkoxy, or fluoroalkyl, a rigid aromatic polyimide having a degree of polymerization (“DP”) of less than about 50 to form an end-capped polyimide; and
 (b) admixing the end-capped polyimide with an uncapped, rigid aromatic polyimide having a DP of greater than about 60, in a ratio of about 1 part end-capped polyimide to about 3 to about 10 parts uncapped polyimide by weight. 
 
     
     
       2. A method according to  claim 1  wherein the DP of the end-capped polyimide is in the range of about 20 to about 50. 
     
     
       3. A method according to  claim 1  wherein the DP of the uncapped polyimide is in the range of about 80 to about 120.